The leading causes of chronic heart disease are all associated with a non-adaptive deposit of fibrous tissue in the heart. Since fibrous tissue interferes with both cardiac function and cardiac filling, it is a major cause of heart failure. Utilizing models of repetitive ischemia and angiotensin II infusion, this proposal intends to investigate the hypothesis that non-adaptive fibrosis of the heart arises from dysfunction of the immune and inflammatory mechanisms, which, under appropriate circumstances, are protective. The proposal studies the cell signaling associated with the uptake of specific inflammatory cells and the mechanisms by which this results in the generation of a specific fibroblast type that is obligate for cardiac fibrosis. We provide evidence that this mechanism is critical to non-adaptive cardiac fibrosis resulting from a variety of pathological causes. The goal of the project is to identify the common factors leading to cardiac fibrosis from diverse chronic cardiac conditions and suggest potential interventions which might mitigate this process.